Operating systems manage the way software applications utilize the hardware of computer systems, such as storage controllers. A fundamental component of operating systems is the operating system kernel (also referred to herein as a “kernel”), which provides secure computer system hardware access to software applications executing on the computer system. Since accessing the hardware can be complex, kernels may implement a set of hardware abstractions to provide a clean and uniform interface to the underlying hardware. The abstractions provided by the kernel provide software developers easier access to the hardware when writing software applications.
Two common techniques for rebooting (i.e. restarting) an operating system are a “cold boot” and a “warm boot”. During a cold boot, power to a computer system's volatile memory is cycled (i.e., turned off and then turned on), and the operating system is rebooted. Since power is cut off to the memory, any contents (i.e., software applications and data) stored in the memory prior to the cold boot are lost. During a warm boot, the operating system reboots while power is still applied to the volatile memory, thereby preserving the contents stored in the volatile memory.
In addition to a warm boot and a cold boot, the Linux operating system offers a method of rapidly booting a new operating system kernel via the kexec function. The kexec function first loads a new kernel into memory and then immediately starts executing the new kernel.